Threaded fasteners are commonly available in a variety of sizes, thread configurations, materials and grades. In certain critical fastening applications, the dimensional tolerances of the fastener may be of significant importance. For example, selected fasteners employed in the construction of civil and military aircraft have been identified as critical to the airworthiness of the aircraft. Accordingly, these fasteners are frequently subjected to enhanced inspection procedures to ensure compliance with established government and/or commercial standards for fastener quality.
An important aspect of the inspection procedure is a determination of the conformity of the threaded fastener with established dimensional standards. In one known method, threaded fasteners may be individually dimensionally inspected using micrometers and similar devices for the measurement of a shank diameter of the fastener and/or the major and minor thread diameters of the fastener. Thread gages typically configured as a “go” or “no-go” devices may also used to accept or reject threaded fasteners that have conforming or non-conforming thread profiles, respectively. Alternately, other devices, such as an optical comparator, may also be used to inspect the thread profile.
Although the foregoing method is suitable for determining the dimensional conformity of threaded fasteners, certain drawbacks nevertheless exist. Manual inspection of relatively large lots of fasteners is generally time consuming, since a reasonable number of the fasteners must be dimensionally inspected in order to attain a statistically significant sample. Moreover, in instances where all of the fasteners in the lot must be inspected for dimensional conformity, significant amounts of inspection time are required. In either case, accurate dimensional measurements may depend upon the skill of the inspector, which may lead to variations in the dimensional data collected from a selected lot of fasteners.
Accordingly, there is a need for systems and methods for rapidly and accurately obtaining dimensional information for threaded fasteners.